Well, thats his name according to the Warstore, and he, along with Domination will be out in November.
Here are a couple of definitions for "Arbiter".
1. One chosen or appointed to judge or decide a disputed issue; an arbitrator.
2. One who has the power to judge or ordain at will: an arbiter of fashion.
1. (Law) a person empowered to judge in a dispute; referee; arbitrator
2. a person having complete control of something
one chosen to settle a controversy; an umpire or arbitrator.
Wild speculations are welcome?